AIRBAGS: A Safety Restraint System of an automobile

INTRODUCTION

Seat belts provided the sole form of safety in cars.

Airbags were developed.A soft pillow to land against in a crash.They are gas-inflated cushions. The first patent on an inflatable crash landing

device was filed during World War II.Airbags are the subject of serious scientific

research and tests.

BASICS OF AIRBAGS

Newton’s second law of motion.

If objects aren’t restrained they will continue moving at the speed of the moving car even if the car is stopped by a collision.

All airbags need to do is slow down the passengers speed to zero.

MAIN PARTS OF AN AIRBAG

Bag Made of thin nylon fabric,folded into a steering wheel

or dashboard or more recently the door or seat.

Sensor Tells the bag to inflate

Inflation system The rapid pulse of hot nitrogen gas to inflate the bag.

WORKING During collision, a mechanical switch is flipped

and an electrical contact takes place. Sensors send an electric current to the inflation

system. Inflation system contains sodium azide and

potassium nitrate. Electric current heats the filament which ignites

the capsule containing Nitrogen gas. The gas expands quickly and inflation of air

bags takes place, which literally bursts from its storage site in the steering wheel.

2 NaN3 → 2 Na + 3 N2 (g)

10 Na + 2 KNO3 → K2O + 5 Na2O + N2 (g)

K2O + Na2O + 2 SiO2 → K2O3Si + Na2O3Si (silicate glass)

This is how it takes place..

MECHANICAL CRASH SENSORS• CRASH SENSOR WITH DAMPING

BALL IN-TUBE SENSOR

THE AIRFLOW GENEARTES AN AERODYNAMIC DRAG FORCE THAT DAMPENS THE BALL MOTION.

• SPRING MASS SENSOR ROLOMITE SENSORRoller- suspended with a tensioned baned.Substantial collision- roller overcomes a spring force and rotates forward.Impact-moving contact of the metallic band touches a fixed contact and closes a circuit.Parameters- distance of trigger - magnitude of the spring.

Future of airbags

Smart Restraint SystemsAdapts its geometry, performance or behavior

to suit various impacts and occupant position.Includes weight sensors. Determine type of occupant in the seat. i.e

child or adult.Detect the distance of passenger from airbags.

MODERN TYPES OF AIRBAGS

Side air bagCars that currently offer side airbags represent

the new wave of occupant protection.Provides protection during side collisons.This prevents the airbag on the undamaged

side of the car from inflating.

Curtain airbags Inflates in front of windows to provide

passengers better head and neck protection. More efficient at tipping and side impacts. Door air bag The door has more space, allowing for a

bigger bag that provides more coverage. Developed by Ford and Renault.

Door-mounted side air bags must begin deploying in mere 5 or 6 milliseconds!

Airbag checks

Turn the key and look at the dashboard to find the airbag light on for 7-10 sec. & then it goes off.

Problems occur when• 1. Light does not come on.

• 2. If light does not go off after the period.

• 3. If light comes while driving.

CONCLUSIONS

Since safety of human life is of high priority, Air bags are of greater importance in the present vehicles.

Safety bags must be implemented for safe riding and for saving precious lives.

Let’s hope every automobile manufacturer implements the same.

References

[1] A Safety Restraint System of an Automobile.

Tasnim N. Shaikh et al. Int. Journal of Engineering Research and Applications www.ijera.com

Vol. 3, Issue 5, Sep-Oct 2013, pp.615-621

[2] A Treatise on crash sensing for automotive airbag systems IEEE /ASME transactions on

Mechatronics, Vol. 7, No. 2, JUNE 2002 by Ching-Yao Chan .

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